Power generating device

ABSTRACT

A power generating device includes an input rotor that is provided to an output shaft of speed up gears so as to be capable of rotating together with the output shaft, an output rotor that is provided to a drive shaft of a generator so as to be capable of rotating together with the drive shaft, and a one-way clutch that is disposed between the input rotor and the output rotor. The one-way clutch connects the input rotor with the output rotor so as to rotate together with the input rotor and the output rotor when the rotation speed of the input rotor exceeds the rotation speed of the output rotor, and the one-way clutch is configured to release the connection between the input rotor and the output rotor when the rotation speed of the input rotor falls below the rotation speed of the output rotor.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2011-198354 filed onSep. 12, 2011 including the specification, drawings and abstract isincorporated herein by reference in its entirety. The disclosure ofJapanese Patent Application No, 2011-253598 filed on Nov. 21, 2011including the specification, drawings and abstract is incorporatedherein by reference in its entirety. The disclosure of Japanese PatentApplication No. 2012-073987 filed on Mar. 28, 2012 including thespecification, drawings and abstract is incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power generating device in whichrotation of a main shaft by external force is increased in speed withspeed up gears to drive a generator.

2. Description of the Related Art

The speed up gears are used for a wind power generating device in orderthat wind force is received with blades to rotate the main shaft that isconnected to the blades and the rotation of the main shaft is increasedin speed to drive the generator. As shown in FIG. 16, the speed up gears202 include a planetary gear mechanism 203 that receives the rotation ofa main shaft 200 to increase the speed, a high-speed gear mechanism 204that receives the rotation of which the speed is increased by theplanetary gear mechanism 203 and further increases the speed of therotation, and an output shaft 205 that outputs running torque of thehigh-speed gear mechanism 204.

The planetary gear mechanism 203 is constructed such that when an inputshaft 203 a that is coupled to the main shaft 200 so as to be capable ofrotating together rotates; a planet carrier 203 b also rotates, andtherefore a sun gear 203 d rotates with increased speed through a planetgear 203 c, and the rotation is transmitted to a low-speed shaft 204 aof the high-speed gear mechanism 204. The high-speed gear mechanism 204is constructed to rotate an intermediate shaft 204 d with increasedspeed through the low-speed gear 204 b and a first intermediate gear 204c when the low-speed shaft 204 a rotates and further rotate the outputshaft 205 with increased speed through a second intermediate gear 204 eand a high-speed gear 204 f. As respective bearings for rotatablysupporting the low-speed shaft 204 a, the intermediate shaft 204 d, andthe output shaft 205 of the speed up gears 202, roller bearings 206 to211 are frequently used (see Japanese Patent Application Publication No.2007-232186 (JP 2007-232186 A), for example).

In addition, a wind power generating device that receives wind forcewith blades to rotate the main shaft which is connected to the bladesand increases the speed of the rotation of the main shaft to drive thegenerator is known. The speed up gears for increasing the rotation ofthe main shaft in speed includes, as shown in FIG. 16 for example, aplanetary gear mechanism 203 that increases the speed of the rotationwhich is received from a main shaft 200, a high-speed gear mechanism 204that further increases the speed of the rotation which is received fromthe planetary gear mechanism 203, and an output shaft 205 that outputsrunning torque of the high-speed gear mechanism 204. The output shaft205 is coupled to a drive shaft of the generator (not shown) so as to becapable of transmitting drive power.

The planetary gear mechanism 203 is constructed such that when therotation of the main shaft 200 is transmitted to the input shaft 203 a,the planet carrier 203 b rotates, and therefore the sun gear 203 drotates with, increased speed through the planet gear 203 c, and therotation is transmitted to the low-speed shaft 204 a of the high-speedgear mechanism 204. In addition, the high-speed gear mechanism 204 isconstructed to rotate the intermediate shaft 204 d with increased speedthrough the low-speed gear 204 b and the first intermediate gear 204 cwhen the rotation is transmitted from the planetary gear mechanism 203to the low-speed shaft 204 a rotates and further rotate the output shaft205 with increased speed through the second intermediate gear 204 e andthe high-speed gear 204 f.

As respective bearings for rotatably supporting the low-speed shaft 204a, the intermediate shaft 204 d, and the output shaft 205 of the speedup gears 202, roller bearings 206 to 211 are frequently, used (see JP2007-232186 A, for example).

SUMMARY OF THE INVENTION

In the wind power generating device, smearing (a phenomenon in whichsurface layer seizure is generated) on the rolling contact surface of aroller or a raceway surface of a turning wheel is generated in theroller bearing that supports the output shaft which rotates at highspeed, and therefore lifetime of the roller bearing may decrease. Theobject of the present invention is to provide a power generating devicethat can effectively prevent the smearing from generating in the rollerbearing that supports the output shaft of the speed up gears.

The inventor of the present application eagerly studied about generatingmechanism of the smearing. As a result, the inventor has found that whenthe rotation speed of the main shaft rapidly decreases by the decreaseof the wind force, the rotation speed of the drive shaft of thegenerator exceeds the rotation speed of the output shaft by inertia ofthe rotor of the generator which has heavy weight, and thereforeso-called torque loss (load loss) occurs, the radial load that isapplied to the roller bearing which supports the output shaft is reducedthrough the torque loss, sliding friction drag between the roller andthe cage that holds the roller exceeds the rolling friction drag betweenthe roller of the roller bearing and the turning wheel, and thus therotation of the roller is delayed. The inventor has also found that whenthe rotation speed of the main shaft rapidly increases by the increaseof the Wind power from the state described above, inertia torque fromthe increased rotation speed is added to increase the radial load thatis applied to the roller bearing which supports the output shaft, andtherefore the roller slips on the contact surface with the turning wheelin a state in which high load is applied to the roller at the moment,the temperature of the contact surface rises, and thus the smearing isgenerated. The inventor accomplished the invention of the presentapplication based on the findings.

Aspects of the present invention relate to a power generating device.The power generating device includes: speed up gears including a mainshaft that rotates by external force, a rotation transmission mechanismthat receives rotation of the main shaft to increase speed of therotation of the main shaft, and a roller bearing that rotatably supportsan output shaft that outputs running torque of the rotation transmissionmechanism; a generator including a drive shaft which is rotated byreceiving rotation of the output shaft and configured to generateelectricity in connection with rotation of a rotor which rotatestogether with the drive shaft; an input rotor provided to the outputshaft to be capable of rotating together with the output shaft; anoutput rotor provided to the drive shaft to be capable of rotatingtogether with the (hive shaft and concentrically arranged on a radialinside or a radial outside of the input rotor; and a one-way clutchdisposed between the input rotor and the output rotor, the one-wayclutch being configured to connect the input rotor with the output rotorto rotate together with the input rotor and the output rotor when arotation speed of the input rotor exceeds a rotation speed of the outputrotor, and the one-way clutch being configured to release a connectionbetween the input rotor and the output rotor when the rotation speed ofthe input rotor falls below the rotation speed of the output rotor.

According to the power generating device that is constructed asdescribed above, the one-way clutch can connect the input rotor with theoutput rotor so as to be capable of rotating together when the rotationspeed of the input rotor exceeds the rotation speed of the output rotorand releases the connection between the input rotor and the output rotorwhen the rotation speed of the input rotor falls below the rotationspeed of the output rotor. That is to say, even when the rotation speedof the output shaft rapidly falls by a drop in the external forcethrough the main shaft, the rotation of the rotor of the generator byinertia can be prevented from being transmitted to the output shaftthrough the drive shaft. Accordingly, the decrease in radial load thatis applied to the roller bearing which supports the output shaft androtation delay of the roller in association with the decrease in theradial load can be inhibited. Therefore, when the rotation speed of themain shaft rapidly increases by the change in the external force fromthe state described above, and high load is applied to the roller, theroller hardly slips on the contact surface with the turning wheel, andtherefore the smearing on the roller bearing can be effectivelyprevented from generating.

The power generating device may include a rolling bearing disposedbetween the input rotor and the output rotor and configured to supportthe input rotor and the output rotor so that the input rotor and theoutput rotor relatively rotate with each other. The one-way clutch mayinclude an outer peripheral surface of an inner ring, an innerperipheral surface of an outer ring, and a roller arranged in each ofplural wedge-shaped spaces formed between the outer peripheral surfaceof the inner ring and the inner peripheral surface of the outer ring.The one-way clutch may be configured to connect the input rotor with theoutput rotor to rotate together with the input rotor and the outputrotor by engaging the roller with the outer peripheral surface of theinner ring and the inner peripheral surface of the outer ring, and theone-way clutch may be configured to release the connection between theinput rotor and the output rotor by disengaging engagement of the rollerwith the outer peripheral surface of the inner ring and the innerperipheral surface of the outer ring. In this case, due to production ofspacing between the inner ring outer peripheral surface and the outerring inner peripheral surface when the engagement of the roller of theone-way clutch with the inner ring outer peripheral surface and theouter ring inner peripheral surface is disengaged, the relative movementof the input rotor and the output rotor with each other in the radialdirection can be prevented by the rolling bearing. Therefore, the inputrotor and the output rotor can be prevented from rattling in the radialdirection during the operation of the power generating device.

The one-way clutch may include an annular cage configured to hold theplural rollers at specified spacing along a circumferential direction, apair of the rolling bearings may be disposed between the input rotor andthe output rotor, and the paired rolling bearings may be arranged onrespective axial sides of the one-way clutch so that each of the pairedrolling bearings is adjacent to the one-way clutch and an axial end ofeach of the paired rolling bearing is capable of coming into contactwith a corresponding one of axial end faces of the annular cage of theone-way clutch. In this case, the axial end faces of the cage of theone-way clutch come into contact with the axial ends of a pair of therolling bearings, and therefore the movement of the cage to the axialsides can be restricted.

The paired rolling bearings may be a pair of cylindrical roller bearingsthat include plural cylindrical rollers and a portion with which endfaces of the plural cylindrical rollers in an axial direction come intosliding contact, and the axial end faces of the annular cage may comeinto contact with the portion in the pair of the cylindrical rollerbearings. In this case, the inner ring rib of the rolling bearing can beused as a member that restricts the axial movement of the cage, andtherefore the structure of the rolling bearing can be simplified.

The inner peripheral surface of the outer ring of the one-way clutch maybe a cylindrical surface, the cylindrical roller bearing may include araceway surface of an outer ring of the cylindrical roller bearing wherethe cylindrical roller bearing rolls, the output rotor may be arrangedon a radial outside of the input rotor, and the inner peripheral surfaceof the outer ring of the one-way clutch and the raceway surface may beformed in an inner peripheral surface of the output rotor. In this case,the output rotor can be used as the outer ring that has the outer ringinner peripheral surface of the one-way clutch and the outer ring thathas the outer ring raceway surface of the respective cylindrical rollerbearing, and therefore the structure of the entire wind device can besimplified.

The output rotor may be removably secured to the drive shaft andarranged to be movable in the axial direction with respect to the inputrotor. In this case, the output rotor can be removed from the inputrotor when the output rotor is removed from the drive shaft and moved inthe axial direction with respect to the input rotor. Accordingly, theouter ring of the one-way clutch and the outer ring of the cylindricalroller bearing can be removed at the same time, and thereforemaintenance tasks of the one-way clutch and the cylindrical rollerbearing can easily be done. In this case, there is no need to move thegenerator, and therefore the maintenance tasks can be done more easily.

According to the power generating device of the present invention, thesmearing can be effectively prevented from generating in the rollerbearing that supports the output shaft of the speed up gears.

In the power generating device, when burn-out of the generator occurs,the drive shaft becomes hard to rotate, the transmission torque from theoutput shaft to the drive shaft becomes excessively high, and the speedup gears receives overload, and therefore there is a possibility thatthe speed up gears may be damaged.

The present invention provides a power generating device that caneffectively prevent the smearing from generating in the roller bearingwhich supports the output shaft of the speed up gears and reduces theload that is applied to the speed up gears in a case where, thetransmission torque from the output shaft to the drive shaft of thegenerator becomes excessively high.

In the power generating device described above, the one-way clutch maybe provided with a torque limiter configured to release the connectionbetween the input rotor and the output rotor when transmission torquefrom the input rotor to the output rotor exceeds an upper limit.

According to the power generating device that is constructed asdescribed above, the one-way clutch can connect the input rotor with theoutput rotor so as to be capable of rotating together when the rotationspeed of the input rotor exceeds the rotation speed of the output rotorand releases the connection between the input rotor and the output rotorwhen the rotation speed of the input rotor falls below the rotationspeed of the output rotor. That is to say, even when the rotation speedof the output shaft rapidly falls by a drop in the external forcethrough the main shaft, the rotation of the rotor of the generator byinertia can be prevented from being transmitted to the output shaftthrough the drive shaft. Accordingly, the decrease in radial load thatis applied to the roller bearing which supports the output shaft androtation delay of the roller in association with the decrease in theradial load can be inhibited. Therefore, when the rotation speed of themain shaft rapidly increases by the change in the external force fromthe state described above, and high load is applied to the roller, theroller hardly slips on the contact surface with the turning wheel, andtherefore the smearing on the roller bearing can be effectivelyprevented from generating.

In addition, the one-way clutch is provided with the torque limiter, andtherefore when the drive shaft becomes hard to rotate by the burn-out ofthe generator, and the transmission torque from the input rotor on theside of the output shaft to the output rotor on the side of the driveshaft exceeds the upper limit (the input rotor is connected to theoutput rotor to be put into a locked state), the torque limiter canrelease the connection between the input rotor and the output rotor.Accordingly, the load that is applied to the speed up gears can bereduced, and the speed up gears can be prevented from being damaged. Inaddition, because the one-way clutch is provided with the torquelimiter, a simplification and size reduction of the structure can be putinto practice in comparison with a case where the one-way clutch and thetorque limiter are provided separately.

The one-way clutch may include an inner peripheral surface of an outerring provided to one of the input rotor and the output rotor, an outerperipheral surface of an inner ring provided to another of the inputrotor and the output rotor and configured to form plural wedge-shapedspaces in a circumferential direction with the inner peripheral surfaceof the outer ring, and a roller arranged in each of the pluralwedge-shaped spaces; the one-way clutch may be configured to connect theinput rotor with the output rotor to rotate together with the inputrotor and the output rotor by engaging the roller with the outerperipheral surface of the inner ring and the inner peripheral surface ofthe outer ring, the one-way clutch may be configured to release theconnection between the input rotor and the output rotor by disengagingengagement of the roller with the outer peripheral surface of the innerring and the inner peripheral surface of the outer ring; and the torquelimiter may be provided with an accommodating recess that is formed inthe outer peripheral surface of the inner ring, and that accommodatesthe roller separated from the wedge-shaped space, when the transmissiontorque exceeds the upper limit, to disengage the engagement of theroller with the outer peripheral surface of the inner ring and the innerperipheral surface of the outer ring.

According to the above structure, when transmission torque from theinput rotor to the output rotor exceeds an upper limit, the roller thatis separated from the wedge-like space is accommodated in theaccommodating recess, and the engagement of the roller with the innerring outer peripheral surface and the outer ring inner peripheralsurface is disengaged. Therefore, the connection from the input rotor tothe output rotor can be released appropriately.

The outer peripheral surface of the inner ring may be provided in theinput rotor, and the torque limiter may be provided with a separationprevention device that prevents the roller in the accommodating recessfrom being separated from the accommodating recess by centrifugal forcedue to rotation of the input rotor. When the input rotor rotates in astate where the roller is accommodated in the accommodating recess, andthe roller moves out of the accommodating recess by the centrifugalforce, there is a possibility of the engagement of the roller with theinner ring outer peripheral surface and the outer ring inner peripheralsurface again. However, the torque limiter of the present inventionincludes the separation prevention device that prevents the roller frombeing separated from the accommodating recess, and therefore such theproblems can be solved.

The separation prevention device may be constructed such that arestricting section that restricts the movement of the rolleraccommodated in the accommodating recess to the radial outside isprotruded in an edge of the accommodating recess in the circumferentialdirection. According to such the structure, if the roller is separatedfrom the accommodating recess to the radial outside by centrifugal forcedue to the rotation of the input rotor, the control section becomes anobstacle to prevent the separation. Therefore, the engagement of theroller with the inner ring outer peripheral surface and the outer ringinner peripheral surface again can be prevented suitably.

A pocket configured to be capable of accommodating the roller may beprovided between the outer peripheral surface of the inner ring and theinner peripheral surface of the outer ring; a cage configured to holdthe rollers at specified spacing along the circumferential direction andan elastic member configured to bias the roller in the pocket toward anarrowing direction of the wedge-shaped space may be provided betweenthe outer peripheral surface of the inner ring and the inner peripheralsurface of the outer ring; and the accommodating recess may be formed tohave a depth in which the roller is positioned in a radial inside withrespect to the elastic member. According to the above structure, whenthe roller separates from the pocket of the cage to enter into theaccommodating recess, the elastic member extends to be positioned in theradial outside of the roller. Therefore, if the roller is separated fromthe accommodating recess to the radial outside by centrifugal force inassociation with the rotation of the input rotor, the elastic memberbecomes an obstacle, and the separation can be prevented.

The elastic member may be provided with a block member that blocks atleast a part of the accommodating recess that accommodates the roller.According to the above structure, when the elastic member is disposed inthe radial outside of the roller that enters into the accommodatingrecess as described above, the block member can block at least a part ofthe accommodating recess and securely prevent the separation of theroller.

According to the power generating device of the present invention, thesmearing can be effectively prevented from generating in the rollerbearing which supports the output shaft of the speed up gears, and theload that is applied to the speed up gears can be reduced in a casewhere the transmission torque from the output shaft to the drive shaftof the generator becomes excessively high. In addition, according to theone-way clutch of the present invention, when the transmission torquefrom the input shaft to the output shaft of the generator becomesexcessively high, the connection between the input rotor and the outputrotor can be preferably released, and furthermore the separation of theroller from the accommodating recess by centrifugal force due to therotation of the input rotor and the engagement of the roller with theinner ring outer peripheral surface and the outer ring inner peripheralsurface can be prevented.

In the wind power generating device, smearing (a phenomenon in whichsurface layer seizure is generated) on the rolling contact surface of aroller or a raceway surface of a turning wheel is generated in theroller bearing that supports the output shaft which rotates at highspeed, and therefore lifetime of the roller bearing may decrease. Thepresent invention provides a power generating device that caneffectively prevent the smearing from generating in the roller bearingthat supports the output shaft of the speed up gears.

The power generating device may include an inertia mass provided to becapable of rotating together with the output rotor.

According to the power generating device that is constructed asdescribed above, the one-way clutch can connect the input rotor with theoutput rotor so as to be capable of rotating together when the rotationspeed of the input rotor exceeds the rotation speed of the output rotorand releases the connection between the input rotor and the output rotorwhen the rotation speed of the input rotor falls below the rotationspeed of the output rotor. That is to say, even when the rotation speedof the output shaft rapidly falls by a drop in the external forcethrough the main shaft, the rotation of the rotor of the generator byinertia can be prevented from being transmitted to the output shaftthrough the drive shaft. Accordingly, the decrease in radial load thatis applied to the roller bearing which supports the output shaft androtation delay of the roller in association with the decrease in theradial load can be inhibited. Therefore, when the rotation speed of themain shaft rapidly increases by the change in the external force fromthe state described above, and high load is applied to the roller, theroller hardly slips on the contact surface with the turning wheel, andtherefore the smearing on the roller bearing can be effectivelyprevented from generating.

In addition, the output rotor is provided with the inertia mass so as tobe capable of rotating together, and therefore the inertia moment of theoutput rotor can be increased. Accordingly, the one-way clutch releasesthe connection between the input rotor and the output rotor, and whenthe output rotor rotates with decreased speed due to the inertia of therotor, the angular acceleration by the deceleration becomes small.Therefore, the rotation speed of the output rotor can be prevented fromrapidly decreasing. That is to say, even when the rotation speed of themain shaft rapidly falls by a drop in the external force, the rotor ofthe generator does not rapidly decreases the rotation speed inassociation with the output rotor but continues to rotate by theinertia, and therefore the average rotation speed of the rotor can beincreased. Therefore, power generation efficiency of the generator canbe improved.

The power generating device may include a rolling bearing disposedbetween the input rotor and the output rotor and configured to supportthe input rotor and the output rotor so that the input rotor and theoutput rotor relatively rotate with each other. The one-way clutch mayinclude, an outer peripheral surface of an inner ring, an innerperipheral surface of an outer ring, and a roller arranged in each ofplural wedge-shaped spaces formed between the outer peripheral surfaceof the inner ring and the inner peripheral surface of the outer ring.The one-way clutch may be configured to connect the input rotor with theoutput rotor to rotate together with the input rotor and the outputrotor by engaging the roller with the outer peripheral surface of theinner ring and the inner peripheral surface of the outer ring. Theone-way clutch may be configured to release the connection between theinput rotor and the output rotor by disengaging engagement of the rollerwith the outer peripheral surface of the inner ring and the innerperipheral surface of the outer ring. In this case, due to production ofspacing between the inner ring outer peripheral surface and the outerring inner peripheral surface when the engagement of the roller of theone-way clutch with the inner ring outer peripheral surface and theouter ring inner peripheral surface is disengaged, the relative movementof the input rotor and the output rotor with each other in the radialdirection can be prevented by the rolling bearing. Therefore, the inputrotor and the output rotor can be prevented from rattling in the radialdirection during the operation of the power generating device.

The one-way clutch may include an annular cage configured to hold theplural rollers at specified spacing along a circumferential direction,and a pair of the rolling bearings may be disposed between the inputrotor and the output rotor. The paired rolling bearings may be arrangedon respective axial sides of the one-way clutch so that each of thepaired rolling bearings is adjacent to the one-way clutch and an axialend of each of the paired rolling bearings is capable of coming intocontact with a corresponding one of axial end faces of the annular cageof the one-way clutch. In this case, the axial end faces of the cage ofthe one-way clutch come into contact with the axial ends of a pair ofthe rolling bearings, and therefore the movement of the cage to theaxial sides can be restricted.

The pair of the rolling bearings may be a pair of cylindrical rollerbearings that include plural cylindrical rollers and a portion withwhich end faces of the plural cylindrical rollers in an axial directioncome into sliding contact, and the axial end faces of the annular cagemay come into contact with the portion in the pair of the cylindricalroller bearings. In this case, the inner ring rib of the rolling bearingcan be used as a member that restricts the axial movement of the cage,and therefore the structure of the rolling bearing can be simplified.

The inner peripheral surface of the outer ring of the one-way clutch maybe a cylindrical surface, the cylindrical roller bearing may include araceway surface of an outer ring of the cylindrical roller bearing wherethe cylindrical roller bearing rolls, the output rotor may be arrangedon a radial outside of the input rotor, and the inner peripheral surfaceof the outer ring of the one-way clutch and the raceway surface may beformed in an inner peripheral surface of the output rotor. In this case,the output rotor can be used as the outer ring that has the outer ringinner peripheral surface of the one-way clutch and the outer ring thathas the outer ring raceway surface of the respective cylindrical rollerbearing, and therefore the structure of the entire wind device can besimplified.

The output rotor may be removably secured to the drive shaft andarranged to be movable in the axial direction with respect to the inputrotor. In this case, the output rotor can be removed from the inputrotor when the output rotor is removed from the drive shaft and moved inthe axial direction with respect to the input rotor. Accordingly, theouter ring of the one-way clutch and the outer ring of the cylindricalroller bearing can be removed at the same time, and thereforemaintenance tasks of the one-way clutch and the cylindrical rollerbearing can easily be done. In this case, there is no need to move thegenerator, and therefore the maintenance tasks can be done more easily.

The power generating device may include: an electromagnetic clutchconfigured to connect the output rotor with the inertia mass so that theoutput rotor and the inertia mass rotate together during energizationand to release the connection between the output rotor and the inertiamass in non-energization; a detection device configured to detect therotation speed of the output rotor; and a control device configured tocontrol to put the electromagnetic clutch into non-energization state atstartup of rotation of the output rotor and to control to energize theelectromagnetic clutch when the detection device detects that the outputrotor reaches a specified rotation speed after the startup of therotation of the output rotor. In this case, the electromagnetic clutchis not energized and the connection between the output rotor and theinertia mass is released until the output rotor reaches the specifiedrotation speed at the startup of the rotation, and therefore the runningtorque that is required to rotate the output rotor up to the specifiedrotation speed can be reduced. Accordingly, time that is required torotate the rotor up to the specified rotation speed through the outputrotor and the drive shaft can be reduced, and therefore the powergeneration efficiency of the generator can be improved more. When thedetection means detects that the output rotor reaches the specifiedrotation speed after the startup of the rotation of the output rotor,the electromagnetic clutch is energized, and the output rotor and theinertia mass are connected so as to be capable of rotating together, andtherefore the inertia moment of the output rotor can be increased.Accordingly, when the one-way clutch releases the connection between theinput rotor and the output rotor, the rotor of the generator does notrapidly decreases the rotation speed in association with the outputrotor but continues to rotate by the inertia, and therefore the averagerotation speed of the rotor can be increased. Therefore, powergeneration efficiency of the generator can be improved more.

The power generating device may include a viscous fluid couplingdisposed between the output rotor and the inertia mass. The viscousfluid coupling may include; i) viscous fluid that transmits a runningtorque of the output rotor to the inertia mass by viscous drag duringlow-speed rotation of the output rotor, and ii) a centrifugal clutchmechanism that transmits the running torque of the output rotor to theinertia mass by using centrifugal force in association with high-speedrotation of the output rotor during the high-speed rotation of theoutput rotor. In this case, when the output rotor rotates at low speedduring the startup of the rotation, the running torque of the outputrotor is transmitted to the inertia mass by viscous drag of the viscousfluid, and therefore the inertia mass increases the speed with lowerangular acceleration than the angular acceleration of the output rotor.In other words, inertia torque by the inertia mass which is applied tothe output rotor at the startup of the rotation of the output rotor canbe reduced, and therefore the running torque that is required toincrease the rotation speed of the output rotor up to the specifiedrotation speed can be reduced. Accordingly, time that is required toincrease the rotation speed of the rotor up to the specified rotationspeed through the output rotor and the drive shaft can be reduced, andtherefore the power generation efficiency of the generator can beimproved. In addition, when the output rotor reaches the specifiedrotation speed to rotate at high speed, the running torque of the outputrotor, is transmitted to the inertia mass through the centrifugal clutchmechanism. Accordingly, the output rotor and the inertia mass areconnected so as to be capable of rotating together, and therefore theinertia moment of the output rotor can be increased. Therefore, when theone-way clutch releases the connection between the input rotor and theoutput rotor, the rotor of the generator does not rapidly decreases therotation speed in association with the output rotor but continues torotate by the inertia, and therefore the average rotation speed of therotor can be increased, and the power generation efficiency of thegenerator can be improved more.

According to the power generating device of the present invention, thesmearing can be effectively prevented from generating in the rollerbearing that supports the output shaft of the speed up gears.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, advantages, and technical and industrial significance ofthis invention will be described in the following detailed descriptionof example embodiments of the invention with reference to theaccompanying drawings, in which like numerals denote like elements, andwherein:

FIG. 1 is a schematic side view that shows a power generating deviceaccording to a first and a second embodiments of the present invention;

FIG. 2 is a cross-sectional view that shows a roller bearing of speed upgears in the power generating device which is shown in FIG. 1;

FIG. 3 is a cross-sectional view that shows a connection part between anoutput shaft of the speed up gears and a drive shaft of a generator inthe power generating device according to the first embodiment and shownin FIG. 1;

FIG. 4 is a cross-sectional view that shows a one-way clutch in thepower generating device according to the first and a third embodiments;

FIG. 5 is a cross-sectional view that shows a connection part between anoutput shaft of the speed up gears and a drive shaft of a generator inthe power generating device according to the second embodiment and shownin FIG. 1;

FIG. 6 is a cross-sectional view that shows a one-way clutch in thepower generating device according to the second embodiment and shown inFIG. 1;

FIG. 7 is a cross-sectional view that shows a part of the one-way clutchin an enlarged scale according to the second embodiment;

FIG. 8 is a cross-sectional view that shows in an enlarged scale a partof the one-way clutch according to the second embodiment in a state inwhich a roller is accommodated in an accommodating recess;

FIG. 9 is a schematic side view that shows a power generating deviceaccording to the third embodiment of the present invention;

FIG. 10 is a cross-sectional view that shows a connection part betweenan output shaft of the speed up gears and a drive shaft of a generatorin the power generating device according to the third embodiment andshown in FIG. 9;

FIG. 11 is a graph that shows a rotational fluctuation of an outputrotor in the power generating device according to the third embodiment;

FIG. 12 is a graph that shows rotational fluctuations of the outputshaft which is shown in FIG. 10 and a rotor of the generator;

FIG. 13 is a cross-sectional view that shows a connection part betweenan output shaft of speed up gears and a drive shaft of a generator in awind power generating device according to a fourth embodiment of thepresent invention;

FIG. 14 is a cross-sectional view that shows a connection part betweenan output shaft of speed up gears and a drive shaft of a generator in awind power generating device according to a fifth embodiment of thepresent invention;

FIG. 15 is a graph that shows rotational fluctuations of an output rotorand an inertia mass in the wind power generating device in FIG. 14; and

FIG. 16 is a cross-sectional view that shows the speed up gears.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to attached drawings. FIG. 1 is a schematic sideview that shows a power generating device according to a first and asecond embodiments of the present invention. The power generating deviceof the present embodiment is a wind power generating device 1. The windpower generating device 1 includes a main shaft 2 that rotates byreceiving wind force (external force), speed up gears 3 that are coupledto the main shaft 2, and a generator 4 that is coupled to the speed upgears 3. The rotation of the main shaft 2 is increased in speed by thespeed up gears 3, and the generator 4 is driven by rotative power withincreased speed.

At a tip end of the main shaft 2, blades (not shown), for example, arecoupled so as to be capable of rotating together, and the blades areconstructed to receive the wind force to rotate together with the mainshaft 2. The generator 4 has a drive shaft 41 that receives the rotativepower with increased speed by the speed up gears 3 to rotate, and arotor 42 that is installed in the generator 4, and a stator (not shown).The rotor 42 is coupled to the drive shaft 41 so as to be capable ofrotating together, and electricity is generated in connection with therotation of the drive shaft 41 and the driving of the rotor 42.

The speed up gears 3 include a gear mechanism (rotation transmissionmechanism) 30 that receives the rotation of the main shaft 2 to increasethe speed of the rotation. The gear mechanism 30 includes a planetarygear mechanism 31 and a high-speed gear mechanism 32 that receives therotation of which the speed is increased by the planetary gear mechanism31 and further increases the speed of the rotation. The planetary gearmechanism 31 has an internal gear (ring gear) 31 a, plural planet gears31 b that are held by a planet carrier (not shown) which is coupled tothe main shaft 2 so as to be capable of rotating together, and a sungear 31 c that meshes with the planet gears 31 b. Accordingly, when theplanet carrier rotates together with the main shaft 2, the sun gear 31 crotates through the planet gears 31 b, and the rotation is transmittedto a low-speed shaft 33 of the high-speed gear mechanism 32.

The high-speed gear mechanism 32 includes the low-speed shaft 33 thathas a low-speed gear 33 a, an intermediate shaft 34 that has a firstintermediate gear 34 a and a second intermediate gear 34 b, and anoutput shaft 35 that has a high-speed gear 35 a. The low-speed shaft 33is formed with a large rotating shaft of which the diameter is about 1 mand concentrically arranged with the main shaft 2. Both ends of thelow-speed shaft 33 in the axial direction are supported by rollerbearings 36 a and 36 b for rotation. The intermediate shaft 34 isarranged above the low-speed shaft 33. Both ends of the intermediateshaft 34 in the axial direction are supported by roller bearings 37 aand 37 b for rotation. The first intermediate gear 34 a on theintermediate shaft 34 meshes with the low-speed gear 33 a, and thesecond intermediate gear 34 b meshes with the high-speed gear 35 a. Theoutput shaft 35 is arranged above the intermediate shaft 34 and adaptedto output the running torque. Sides of one end 35 b and another end(output end) 35 c of the output shaft 35 in the axial direction arerespectively supported by roller bearings 38 and 39 for rotation.

According to the above structure, the rotation of the main shaft 2 isincreased in speed in three stages with a gear ratio of the planetarygear mechanism 31, a gear ratio between the low-speed gear 33 a and thefirst intermediate gear 34 a, and a gear ratio between the secondintermediate gear 34 b and the high-speed gear 35 a. The running torqueis output from the output end 35 c of the output shaft 35. Therefore,the rotation of the main shaft 2 by the wind force is increased in speedin three stages by the speed up gears 3 and adapted to drive thegenerator 4.

FIG. 2 is a cross-sectional view that shows the roller bearing 38 whichsupports one end 35 b of the output shaft 35. In FIG. 2, the rollerbearing 38 is formed by a cylindrical roller bearing and includes aninner ring 38 a that is fitted and fixed onto the output shaft 35, anouter ring 38 b that is fixed to a housing (not shown), pluralcylindrical rollers 38 c that are placed between the inner ring 38 a andthe outer ring 38 b so as to be capable of rolling, and an annular cage38 d that holds respective cylindrical rollers 38 c at specified spacingalong the circumferential direction. The inner ring 38 a, the outer ring38 b, and the cylindrical roller 38 c are made of bearing steel, forexample. The cage 38 d is made of a copper alloy, for example.

The inner ring 38 a has an inner ring raceway surface 38 a 1 that isformed at an axial center of the outer periphery. The outer ring 38 b isconcentrically arranged with the inner ring 38 a and has an outer ringraceway surface 38 b 1 that is formed at an axial center of the innerperiphery and a pair of outer ring ribs 38 b 2 that are formed in axialsides of the outer ring raceway surface 38 b 1. The outer ring racewaysurface 38 b 1 is arranged to face the inner ring raceway surface 38 a1. The outer ring ribs 38 b 2 are formed to protrude from both ends ofthe inner periphery of the outer ring 38 b in the axial direction to aninner side in a radial direction. An end face of the cylindrical roller38 c comes into sliding contact with the outer ring ribs 38 b 2.

The cylindrical roller 38 c is placed between the inner ring racewaysurface 38 a 1 of the inner ring 38 a and the outer ring raceway surface38 b 1 of the outer ring 38 b so as to be capable of rolling. The cage38 d has a pair of annular sections 38 d 1 that are separately placed inthe axial direction and plural column sections 38 d 2 that are placed atequal spacing along the circumferential direction of the annularsections 38 d 1 to connect both of the annular sections 38 d 1. Pockets38 d 3 are respectively formed between the pair of annular sections 38 d1 and the adjacent column sections 38 d 2, and the respectivecylindrical rollers 38 c are placed in the pockets 38 d 3.

As shown in FIG. 1, the wind power generating device 1 further includesan input rotor 5 that is provided so as to be capable of rotatingtogether with the output shaft 35 of the speed up gears 3, an outputrotor 6 that is provided so as to be capable of rotating together withthe drive shaft 41 of the generator 4, a one-way clutch 7 that isdisposed between the input rotor 5 and the output rotor 6, and a pair ofrolling bearings 8 that are disposed on axial sides of the one-wayclutch 7. The one-way clutch 7 and the rolling bearings 8 areconstructed to transmit the rotation of the output shaft 35 to the driveshaft 41 through the input rotor 5 and the output rotor 6. Here, thewind power generating device 1 of the present embodiment is constructedsuch that the rolling bearings 8 are disposed in the axial sides of theone-way clutch 7; however, a rolling bearing 8 may be disposed in onlyone axial side of the one-way clutch 7.

First, the first embodiment will be described. FIG. 3 is across-sectional view that shows a connection part between the outputshaft 35 of the speed up gears 3 and the drive shaft 41 of the generator4. In FIG. 3, the input rotor 5 is concentrically arranged with theoutput shaft 35 and has a flange section 51, a large diameter section52, and a small diameter section 53 in this order from one axial end(left end of FIG. 3) to another axial end (right end of FIG. 3). Theflange section 51 is formed to extend to a radial outside beyond theouter peripheral surface of the large diameter section 52 and removablysecured in the output end 35 e of the output shaft 35. Specifically, theflange section 51 is fastened on a flange section 35 c 1 that is formedin the output end 35 c in an abutting state against the flange section35 c 1 with a bolt and a nut (not shown). A spacing S1 is formed betweenthe end face of the small diameter section 53 and the end face of aflange section 41 a of the drive shaft 41.

The output rotor 6 is concentrically arranged on a radial outside of theinput rotor 5 and has a cylindrical section 61 and a flange section 62that is formed in another axial end (right end of FIG. 3) of thecylindrical section 61. The flange section 62 is formed to extend to aradial outside beyond the outer peripheral surface of the cylindricalsection 61 and removably secured in one end of the drive shaft 41.Specifically, the flange section 62 is fastened on a flange section 41 athat is formed in one end of the drive shaft 41 in an abutting stateagainst the flange section 41 a with a bolt and a nut (not shown).

An inner peripheral surface of the cylindrical section 61 is formed in acylindrical surface. An annular seal member 10 for sealing an annularspace between the cylindrical section 61 and the small diameter section53 of the input rotor 5 is disposed in the spacing between the innerperipheral surface of the cylindrical section 61 in one axial end (leftend of FIG. 3) and the outer peripheral surface of the large diametersection 52 of the input rotor 5. A spacing S2 is formed between an endface of the cylindrical section 61 on one end side and an end face ofthe flange section 51 of the input rotor 5 that faces the end face ofthe cylindrical section 61. Accordingly, the output rotor 6 can move toboth axial sides with respect to the input rotor 5 in a state in whichthe output rotor 6 is separated from the drive shaft 41.

FIG. 4 is a cross-sectional view that shows the one-way clutch 7. InFIG. 3 and FIG. 4, the one-way clutch 7 includes an inner ring 71, anouter ring 72, and plural rollers 73 that are disposed between an outerperipheral surface 71 a of the inner ring 71 and an inner peripheralsurface 72 a of the outer ring 72. The inner ring 71 is fitted andsecured onto the axial center of the small diameter section 53 of theinput rotor 5 and constructed to rotate together with the small diametersection 53. A region B in the axial center of the cylindrical section 61of the output rotor 6 is set as the outer ring 72 of the one-way clutch7. Therefore, the inner peripheral surface 72 a is formed in an innerperipheral surface of the cylindrical section 61 in the region B. Therollers 73 are formed in a circular cylindrical shape, and eight rollersare disposed in the circumferential direction in the present embodiment.

The one-way clutch 7 further includes an annular cage 74 that holdsrespective rollers 73 at specified spacing along the circumferentialdirection and plural elastic members 75 that elastically bias therespective rollers 73 toward one direction. The cage 74 has a pair ofannular sections 74 a that face each other in the axial direction andplural column sections 74 b that extend between both annular sections 74a in the axial direction and are arranged at equal spacing in thecircumferential direction to connect both annular sections 74 a. Pluralpockets 74 c are formed between both annular sections 74 a and theadjacent column sections 74 b, and the respective rollers 73 areseparately accommodated in the respective pockets 74 c. The elasticmembers 75 are formed with a helical compression spring and separatelyaccommodated in the respective pockets 74 c of the cage 74 to beinstalled in the column sections 74 b.

In FIG. 4, flat cam surfaces 71 a 1 that have the same number as therollers 73 (eight) are formed in the outer peripheral surface 71 a ofthe inner ring 71. The inner peripheral surface 72 a of the outer ring72 is formed to be a cylindrical surface. Plural (eight) wedge-shapedspaces S are formed in the circumferential direction between the camsurfaces 71 a 1 of the inner ring 71 and the cylindrical surface of theouter ring 72. The rollers 73 are separately arranged in the respectivewedge-shaped spaces S, and the elastic members 75 bias the rollers 73toward the direction in which the wedge-shaped spaces S become narrow.The outer peripheral surface of a roller 73 is formed to be a contactsurface 73 a that comes into contact with a cam surface 71 a 1 of theinner ring 71 and a cylindrical surface of the outer ring 72, and thecontact surface 73 a is formed straight in a width direction (axialdirection). The one-way clutch 7 is placed in an environment wheregrease as lubricant that is made from ester base oil and a urea-basedthickener and hardly affected by temperature changes is provided betweenthe inner ring 71 and the outer ring 72.

In the one-way clutch 7 that is constructed as described above, in acase where the input rotor 5 rotates with increased speed and thereforethe rotation speed of the input rotor 5 exceeds that of the output rotor6, the inner ring 71 makes relative rotation to the outer ring 72 in onedirection (counterclockwise direction of FIG. 4). In this case, theroller 73 slightly moves to the direction in which the wedge-shapedspace S becomes narrow by the biasing force of the elastic member 75,the contact surface 73 a of the roller 73 is brought into contact withthe outer peripheral surface 71 a of the inner ring 71 and the innerperipheral surface 72 a of the outer ring 72 (i.e., the roller 73 ispressed toward the inner ring 71 and the outer ring 72), and the one-wayclutch 7 becomes a state in which the roller 73 engages between theinner ring 71 and the outer ring 72. Accordingly, the inner ring 71 andthe outer ring 72 can rotate together in one direction and connect theinput rotor 5 with the output rotor 6 so as to be capable of rotatingtogether.

In a case where the rotation speed of the input rotor 5 becomes constantafter increasing and the same speed as that of the output rotor 6, theroller 73 is kept in an engagement state between the inner ring 71 andthe outer ring 72. Therefore, the one-way clutch 7 maintains corotationof the inner ring 71 and the outer ring 72 in one direction, and theinput rotor 5 and the output rotor 6 continue to rotate together.

On the other hand, in a case where the input rotor 5 rotates withdecreased speed and therefore the rotation speed of the input rotor 5falls below that of the output rotor 6, the inner ring 71 makes relativerotation to the outer ring 72 in another direction (clockwise directionof FIG. 4). In this case, the roller 73 slightly moves to the directionin which the wedge-shaped space S becomes wide against the biasing forceof the elastic member 75, and therefore the engagement of the roller 73with the inner ring 71 and the outer ring 72 is disengaged. Accordingly,the engagement of the roller 73 is disengaged, and therefore theconnection between the input rotor 5 and the output rotor 6 is released.

In FIG. 3, a pair of rolling bearings 8 are respectively disposedbetween the small diameter section 53 of the input rotor 5 and thecylindrical section 61 of the output rotor 6 and support the input rotor5 and the output rotor 6 for relative rotation with each other. Therolling bearings 8 are arranged on the axial sides of the one-way clutch7 adjacent to each other so that the axial ends of the rolling bearings8 can come into contact with the axial end faces of the cage 74 of theone-way clutch 7 in the axial end.

A rolling bearing 8 is provided with an inner ring 81, an outer ring 82,and a cylindrical roller bearing that includes plural cylindricalrollers 83 which are placed between the inner ring 81 and the outer ring82 so as to be capable of rolling. The inner ring 81 has an inner ringraceway surface 81 a that is formed in an outer periphery and an innerring rib 81 b that is formed on axial sides of the inner raceway surface81 a to protrude toward a radial outside. End faces of the cylindricalroller 83 respectively come into sliding contact with an inner surfaceof the inner ring rib 81 b. In addition, an outer surface 81 b 1 of theinner ring rib 81 b adjacent to the one-way clutch 7 is formed to be acontact surface that comes into contact with an outer surface of theannular section 74 a which is an axial end face of the cage 74 of theone-way clutch 7.

Regions A and C in axial end faces of the cylindrical section 61 of theoutput rotor 6 are set as the outer ring 82 of the rolling bearing 8. Anouter ring raceway surface 82 a of the outer ring 82 is formed inrespective inner peripheral surfaces of the regions A and C. Thecylindrical roller 83 is placed between the outer ring raceway surface82 a and the inner ring raceway surface 81 a so as to be capable ofrolling.

According to the wind power generating device 1 that is constructed asdescribed above, the one-way clutch 7 that is disposed between the inputrotor 5 which rotates together with the output shaft 35 of the speed upgears 3 and the output rotor 6 which rotates together with the driveshaft 41 of the generator 4 can release the connection between the inputrotor 5 and the output rotor 6 when the rotation speed of the inputrotor 5 falls below that of the output rotor 6. That is to say, when therotation speed of the output shaft 35 rapidly falls by a drop in thewind force through the main shaft 2, the rotation of the rotor 42 of thegenerator 4 by inertia can be prevented from being transmitted to theoutput shaft 35 through the drive shaft 41. Accordingly, the decrease inradial load that is applied to the roller bearing 38 which supports theoutput shaft 35 and rotation delay of the cylindrical roller 38 c inassociation with the decrease in the radial load can be inhibited.Therefore, when the rotation speed of the main shaft 2 rapidly increasesby the change in the wind force and high load is applied to thecylindrical roller 38 from the above state, the cylindrical roller 38 chardly slides on the contact surface with the inner ring 38 a, andtherefore the production of smearing on the roller bearing 38 can beinhibited effectively.

In addition, by preventing the rotation of the rotor 42 of the generator4 by inertia from being transmitted to the output shaft 35, loads thatare applied to the roller bearings 36 a, 36 b, 37 a, 37 b, 38, 39, andthe like of the speed up gears 3 can be reduced. Accordingly, the sizereduction of all of the gears 31 b and 31 c of the planetary gearmechanism 31, the shafts 33 through 35 of the high-speed gear mechanism32, and the roller bearings 36 a, 36 b, 37 a, 37 b, 38, and 39 can beachieved, and therefore the speed up gears 3 can be reduced in weightand manufactured at low cost. Furthermore, by releasing the connectionbetween the input rotor 5 and the output rotor 6, the rotor 42 of thegenerator 4 continues to rotate by inertia without rapid slow down, andtherefore average rotation speed of the rotor 42 can be increased.Accordingly, power generation efficiency of the generator 4 can beimproved.

Between the input rotor 5 and the output rotor 6, the rolling bearing 8that supports the rotors so as to be capable of relatively rotating toeach other is disposed. Thus, by releasing the engagement of the roller73, the inner ring 71, and the outer ring 72 in the one-way clutch 7,when the spacing between the roller 73 and the inner and the outer rings71 and 72 is produced in the wedge-shaped spacing S, the rolling bearing8 can prevent the input rotor 5 and the output rotor 6 from relativelymoving to each other in the radial direction. Therefore, the input rotor5 and the output rotor 6 can be prevented from rattling in the radialdirection during the operation of the wind power generating device 1.

Because a pair of the rolling bearings 8 are arranged on the axial sidesof the one-way clutch 7 adjacent to each other, and the axial end facesof the cage 74 of the one-way clutch 7 are formed to be capable ofcontact with the axial ends of the rolling bearings 8, the movement ofthe cage 74 to the axial sides can be restricted. Specifically, becausethe axial end face of the cage 74 of the one-way clutch 7 (outer surfaceof the annular section 74 a) comes into contact with the inner ring rib81 b of the rolling hearing 8, the inner ring rib 81 b of the rollingbearing 8 can also be used as a member that restricts the axial movementof the cage 74. Accordingly, the structure of the rolling bearing 8 cansimplified.

In addition, because the outer ring inner peripheral surface 72 a of theone-way clutch 7 and the outer ring raceway surface 82 a of the rollingbearing 8 are formed in the inner peripheral surface of the output rotor6, the output rotor 6 can be used as the outer ring 72 of the one-wayclutch 7 and the outer ring 82 of the rolling bearing 8. Accordingly,the structure of the entire wind power generating device 1 can besimplified. Because the output rotor 6 is removably secured to the driveshaft 41 of the generator 4 and arranged in a movable manner in theaxial direction with respect to the input rotor 5, the output rotor 6can be removed from the input rotor 5 when the output rotor 6 is removedfrom the drive shaft 41 and moved in the axial direction with respect tothe input rotor 5. Accordingly, the outer ring 72 of the one-way clutch7 and the outer ring 82 of the rolling bearing 8 can be removed at thesame time, and therefore maintenance tasks of the one-way clutch 7 andthe rolling bearing 8 can easily be done. In this case, there is no needto move the generator 4, and therefore the maintenance tasks can be donemore easily.

The present invention is not limited to the first embodiment describedabove and can be changed appropriately to be practiced. For example, inthe first embodiment, the input rotor and the output rotor arerespectively provided to the output shaft and the drive shaft asseparate members; however, the input rotor and the output rotor mayintegrally be formed with the output shaft and the drive shaft,respectively. The output rotor is arranged on the radial outside of theinput rotor; however, the output rotor may be arranged on the radialinside of the input rotor. In this case, the one-way clutch may beformed with the cam surface in the outer ring inner peripheral surface,and the inner ring outer peripheral surface may be formed as thecylindrical surface. Furthermore, in this case, the inner ring outerperipheral surface may be formed in the outer peripheral surface of theoutput rotor, and the output rotor may be used as the inner ring.

In addition, the output rotor is formed as the outer ring of the one-wayclutch and the outer ring of the rolling bearing; however, these outerrings may be provided to the output rotor as separate members. Therolling bearing that is disposed between the input rotor and the outputrotor is constructed as the cylindrical roller bearing in order to movethe output rotor in the axial direction; however, the rolling bearingmay be constructed as a ball bearing in a case where the output rotor isnot moved in the axial direction.

The cage of the one-way clutch comes into contact with the inner ring ofthe rolling bearing; however, the outer ring of the rolling bearing maybe provided to the output rotor as a separate member, and the outer ringmay come into contact with the cage of the one-way clutch. The powergenerating device of the present embodiment is exemplified in a case ofusing wind force as external force; however, the power generating deviceof the present embodiment may be applicable to the power generatingdevice that generates electricity by using other external force such aswaterpower or thermal power.

Next, the structure of the power generating device of the secondembodiment in regard to the one-way clutch will be described.Descriptions of the structure that overlaps with the first embodimentare not, repeated. FIG. 5 is a cross-sectional view that shows aconnection part between the output shaft 35 of the speed up gears 3 andthe drive shaft 41 of the generator 4. In FIG. 5, the input rotor 5 isconcentrically arranged with the output shaft 35 and has a flangesection 51, a large diameter section 52 a, a medium diameter section 52b, and a small diameter section 52 c in this order from one axial end(left end of FIG. 5) to another axial end (right end of FIG. 5).

The flange section 51 is formed to extend to a radial outside beyond theouter peripheral surface of the large diameter section 52 a andremovably secured in the output end 35 c of the output shaft 35.Specifically, the flange section 51 is fastened on a flange section 35 c1 that is formed in the output end 35 c of the output shaft 35 in anabutting state against the flange section 35 c 1 with a bolt and a nut(not shown). A spacing S1 is formed between the end face of the smalldiameter section 52 c and the end face of the flange section 41 a of thedrive shaft 41.

The output rotor 6 is concentrically arranged on a radial outside of theinput rotor 5 and has a cylindrical section 61 and a flange section 62that is formed in another axial end (right end of FIG. 5) of thecylindrical section 61. The flange section 62 is formed to extend to aradial outside beyond the outer peripheral surface of the cylindricalsection 61 and removably secured in one end (left end of FIG. 5) of thedrive shaft 41. Specifically, the flange section 62 is fastened on aflange section 41 a that is formed in one end of the drive shaft 41 inan abutting state against the flange section 41 a with a bolt and a nut(not shown).

An inner peripheral surface of the cylindrical section 61 is formed in acylindrical surface. Au annular seal member 10 for sealing an annularspace between the cylindrical section 61 and the medium diameter section52 b and the small diameter section 52 c of the input rotor 5 isdisposed in the spacing between the inner peripheral surface of thecylindrical section 61 in one axial end (left end of FIG. 5) and theouter peripheral surface of the large diameter section 52 a of the inputrotor 5. A spacing 52 is formed between an end face of the cylindricalsection 61 on one end side and an end face of the flange section 51 ofthe input rotor 5 that faces the end face of the cylindrical section 61.Accordingly, the output rotor 6 can move to both axial sides withrespect to the input rotor 5 in a state in which the output rotor 6 isseparated from the drive shaft 41.

FIG. 6 is a cross-sectional view that shows the one-way clutch 7, andFIG. 7 is a cross-sectional view that shows a part of the one-way clutch7 in an enlarged scale. In FIG. 5 through FIG. 7, the one-way clutch 7includes an inner ring 71, an outer ring 72, and plural rollers 73 thatare disposed between an outer peripheral surface 71 a of the inner ring71 and an inner peripheral surface 72 a of the outer ring 72. The innerring 71 is fitted and secured onto a left side of the small diametersection 52 c of the input rotor 5 and constructed to rotate togetherwith the small diameter section 52 e in a direction of an arrow A ofFIG. 6. A region B in the axial center of the cylindrical section 61 ofthe output rotor 6 is set as the outer ring 72 of the one-way clutch 7.Therefore, the inner peripheral surface 72 a is formed in an innerperipheral surface of the cylindrical section 61 in the region B. Therollers 73 are formed in a circular cylindrical shape, and six rollersare disposed in the circumferential direction in the present embodiment.

In FIG. 6, flat cam surfaces 71 a 1 that have the same number as therollers 73 (six) are formed in the outer peripheral surface 71 a of theinner ring 71. The inner peripheral surface 72 a of the outer ring 72 isformed to be a cylindrical surface. Plural (six) wedge-shaped spaces Sare formed in the circumferential direction between the cam surfaces 71a 1 of the inner ring 71 and the cylindrical surface 72 a of the outerring 72. The rollers 73 are separately arranged in the respectivewedge-shaped spaces 8, and the elastic members 75 bias the rollers 73toward the direction in which the wedge-shaped spaces S become narrow(narrowing direction). The outer peripheral surface of a roller 73 isformed to be a contact surface that comes into contact with a camsurface 71 a 1 of the inner ring 71 and a cylindrical surface 72 a ofthe outer ring 72. The one-way clutch 7 is placed in an environmentwhere grease as lubricant that is made from ester base oil and aurea-based thickener and hardly affected by temperature changes isprovided between the inner ring 71 and the outer ring 72.

In the one-way clutch 7 that has a structure as described above, in acase where the input rotor 5 rotates with increased speed and thereforethe rotation speed of the input rotor 5 exceeds that of the output rotor6, the inner ring 71 makes relative rotation to the outer ring 72 in onedirection (direction of the arrow A (counterclockwise direction) of FIG.6). In this case, the roller 73 slightly moves to the direction in whichthe wedge-shaped space S becomes narrow by the biasing force of theelastic member 75, the outer peripheral surface of the roller 73 isbrought into contact with the outer peripheral surface 71 a (cam surface71 a 1) of the inner ring 71 and the inner peripheral surface 72 a ofthe outer ring 72 (i.e., the roller 73 is pressed toward the inner ring71 and the outer ring 72), and the roller 73 becomes a state of engagingbetween the inner ring 71 and the outer ring 72. Accordingly, the innerring 71 and the outer ring 72 rotate together in the direction of thearrow A, and the input rotor 5 and the output rotor 6 are connected soas to be capable of rotating together.

In a case where the rotation speed of the input rotor 5 becomes constantafter increasing and the same speed as that of the output rotor 6, theroller 73 is kept in an engagement state between the inner ring 71 andthe outer ring 72. Therefore, the inner ring 71 and the outer ring 72maintain corotation in the direction of the arrow A, and the input rotor5 and the output rotor 6 continue to rotate together.

On the other hand, in a case where the input rotor 5 rotates withdecreased speed and therefore the rotation speed of the input rotor 5falls below that of the output rotor 6, the inner ring 71 makes relativerotation to the outer ring 72 in another direction (opposite directionof the arrow A (clockwise direction) of FIG. 6). In this case, theroller 73 slightly moves to the direction in which the wedge-shapedspace S becomes wide against the biasing force of the elastic member 75,and therefore the engagement state of the outer peripheral surface ofthe roller 73 with the inner ring 71 and the outer ring 72 isdisengaged. Accordingly, the connection between the input rotor 5 andthe output rotor 6 is released.

The wind power generating device 1 that is the power generating deviceof the second embodiment produces a similar effect to the wind powergenerating device 1 of the first embodiment.

The one-way clutch 7 of the present embodiment is provided with a torquelimiter 9. The torque limiter 9 is adapted to release the connectionbetween the input rotor 5 and the output rotor 6 in a case where runningtorque that is transmitted from the input rotor 5 to the output rotor 6exceeds a specified value (upper limit). As described above, the one-wayclutch 7 is constructed such that the input rotor 5 rotates in thedirection of the arrow A with increased speed, and therefore the roller73 engages between the earn surface 71 a 1 and the inner peripheralsurface 72 a of the outer ring 72 and makes the output rotor 6 rotatetogether in the direction of the arrow A. However, when burn-out of thegenerator 4 occurs and the drive shaft 41 becomes hard to rotate, theoutput rotor 6 that is coupled to the drive shaft 41 also becomes hardto rotate, and the running torque that is transmitted from the inputrotor 5 to the output rotor 6 becomes excessively high. Thus, the speedup gears 3 between the output shaft 35 that is coupled to the inputrotor 5 and the main shaft 2 receives overload, and there is apossibility that gears and bearings in the speed up gears 3 may bedamaged.

The torque limiter 9 of the present embodiment is provided for solvingthe disadvantages as described above and has an accommodating recess 91that is formed in the outer peripheral surface 71 a of the inner ring 71and can accommodate the roller 73 as shown in FIG. 6 and FIG. 7. Theaccommodating recess 91 is formed in a corresponding position betweenthe cam surfaces 71 a 1 next to each other in the circumferentialdirection. Therefore; a total of six accommodating recesses 91 areformed in the present embodiment. The roller 73 that comes into contactwith the cam surface 71 a 1 which is adjacently arranged in thedirection of the arrow A is adapted to fall and be accommodated into theaccommodating recess 91 when the roller 73 passes over an end section 71a 2 of the cam surface 71 a 1.

As shown in FIG. 7, a bottom section 91 a of the accommodating recess 91is formed in an arc surface that has approximately same radius as thatof the roller 73. Side wall sections 91 b 1 and 91 b 2 that are formedin circumferential directions of the bottom section 91 a are formed inparallel with each other and in inclined surfaces that are inclined withrespect to an imaginary line Y in the radial direction which passesthrough a shaft center O of the one-way clutch 7 and a center ofcurvature of the bottom section 91 a so that the radial outside of theside wall section is located in the direction of the arrow A. Therefore,the side wall section 91 b 1 in the vicinity of the roller 73 which isnot accommodated in the accommodating recess 91 and is located betweenthe cam surface 71 a 1 and the inner peripheral surface 72 a of theouter ring 72 is formed to be long in length, and the side wall section91 b 2 on a far side from the roller 73 is formed to be short in length.In addition, an angle between the cam surface 71 a 1 and a surface ofthe side wall section 91 b 1 is set to 90° or greater (for example,about 90° through 120°).

The accommodating recess 91 is formed to have a depth in which theentire roller 73 can be accommodated. Therefore, the roller 73 that isaccommodated in the accommodating recess 91 is positioned in a radialinside with respect to the elastic member 75. The elastic member 75 isprovided with a cover member 93. The cover member 93 is formed, as shownin FIG. 7, in a bottomed square tube shape so as to surround onecircumferential end face (end face on a side of the roller 73), a radialouter surface, a radial inner surface, and axial side surfaces of theelastic member 75. A section 93 a that covers one circumferential endface comes into contact with the roller 73, A section 93 b that coversthe radial outer surface of the elastic member 75 is formed in an arcshape along the inner peripheral surface 72 a of the outer ring 72. Acoating of fluorocarbon polymers or molybdenum disulfide is applied tothe section 93 b so that the section 93 b can smoothly slide when cominginto contact with the inner peripheral surface 72 a of the outer ring72, and therefore friction drag is reduced.

When the running torque that is transmitted from the input rotor 5 tothe output rotor 6 exceeds the upper limit, the roller 73 passes overthe end section 71 a 2 from the cam surface 71 a 1, drops into theaccommodating recess 91 as shown in FIG. 8, and is separated from thewedge-shaped space S between the cam surface 71 a 1 and the innerperipheral surface 72 a of the outer ring 72. Therefore, the connectionbetween the input rotor 5 and the output rotor 6 is fully released, andthe transmission of the running torque between both rotors is cut off.Thus, the input rotor 5 rotates nearly freely from load, the load thatis applied to the speed up gears 3 can be reduced, and the speed upgears 3 can be prevented from being damaged.

The input rotor 5 continues to rotate with the increased speed by thespeed up gears 3 as long as the main shaft 2 rotates after the roller 73is accommodated into the accommodating recess 91. However, when theroller 73 is separated from the accommodating recess 91 toward theradial outside by centrifugal force due to the rotation of the inputrotor 5 and again engages between the cam surface 71 a 1 and the innerperipheral surface 72 a of the outer ring 72, the input rotor 5 isconnected to the output rotor 6 to be locked, and the speed up gears 3receives large, load. In order to prevent such the problem, the torquelimiter 9 of the present embodiment is provided with separationprevention means (separation prevention device) that prevent theseparation of the roller 73 from the accommodating recess 91.

Specifically, the separation prevention means is constructed such thatone side wall section (that is, a control section that is an edge in thecircumferential direction) 91 b 2 of the accommodating recess 91protrudes toward the radial outside of the roller 73. That is, if theroller 73 moves to the radial outside (a direction of a hollow arrow Balong the imaginary line Y) by the centrifugal force, the side wallsection 91 b 2 of the accommodating recess 91 becomes an obstacle to themovement of the roller 73, and the separation of the roller 73 from theaccommodating recess 91 can be prevented. Because inertial forceopposite to the direction of the arrow A is imparted to the roller 73 bythe rotation of the input rotor 5 in the direction of the arrow A, theroller 73 is more hardly separated from the accommodating recess 91.

In addition, the separation prevention means is also constructed withthe elastic member 75 and the cover member 93. That is, when the roller73 on the earn surface 71 a 1 drops into the accommodating recess 91,the elastic member 75 in the pocket 74 c extends, the roller 73 ispositioned in the radial inside of the elastic member 75 and the covermember 93, and at least a part of the accommodating recess 91 is blockedby the cover member 93. Therefore, if the roller 73 moves to the radialoutside by the centrifugal force due to the rotation of the input rotor5, the elastic member 75 and the cover member 93 become the obstacles tothe movement of the roller 73, and separation of the roller 73 from theaccommodating recess 91 can be prevented suitably. Particularly, theseparation of the roller 73 from the accommodating recess 91 cansecurely be prevented by providing the cover member 93 to the elasticmember 75.

In FIG. 5, a pair of the rolling bearings 8 are respectively disposedbetween the medium diameter section 52 b of the input rotor 5 and thecylindrical section 61 of the output rotor 6 and between an intermediatering body 53 that is fitted to the small diameter section 52 e of theinput rotor 5 so as to be capable of rotating together and thecylindrical section 61. The pair of the rolling bearings 8 support theinput rotor 5 and the output rotor 6 each other for relative rotation.The rolling bearings 8 are adjacently arranged on the axial sides of theone-way clutch 7 so that the axial ends of the rolling bearings 8 cancome into contact with the axial end faces of the cage 74 of the one-wayclutch 7.

The present invention is not limited to the second embodiment describedabove and can be changed appropriately to be practiced. For example, inthe second embodiment, the output rotor is formed as the outer ring ofthe one-way clutch and the outer ring of the rolling bearing; however,these outer rings may be provided to the output rotor as separatemembers. On the other hand, the input rotor can be formed as the innerring of the one-way clutch and the inner ring of the rolling bearing.The rolling bearing that is disposed between the input rotor and theoutput rotor is constructed as the cylindrical roller bearing in orderto move the output rotor in the axial direction; however, the rollingbearing may be constructed as a ball bearing in a case where the outputrotor is not moved in the axial direction.

The accommodating recess of the torque limiter may not be necessarilyformed in a depth that can accommodate the entire roller but may beformed deeper than at least the radius of the roller. When theaccommodating recess is formed deeper than the radius of the roller, thecontrol section can be formed without protruding from the innerring-outer peripheral surface. The cage of the one-way clutch comes intocontact with the inner ring of the rolling bearing; however, the outerring of the rolling bearing may be provided to the output rotor as aseparate member, and the outer ring may come into contact with the cageof the one-way clutch. Furthermore, the present embodiment exemplifiesthe wind power generating device that uses wind force as external force;however, the present invention may be applicable to the power generatingdevice that generates electricity by using other external force such aswaterpower or thermal power. The one-way clutch of the present inventionis also applicable to applications other than the power generatingdevice.

On example of the one-way clutch according to the present invention isdisposed between the input rotor and the output rotor that isconcentrically arranged on the radial outside of the input rotor,connects the input rotor with the output rotor so as to be capable ofrotating together in a state where the rotation speed of the input rotorexceeds that of the output rotor, and releases the connection betweenthe input rotor and the output rotor in a state where the rotation speedof the input rotor falls below that of the output rotor. The one-wayclutch includes the inner peripheral surface of the outer ring, theouter peripheral surface of the inner ring, the roller and the torquelimiter. The inner peripheral surface of the outer ring is provided onthe side of the output rotor. The outer peripheral surface of the innerring is provided on the side of the input rotor and forms pluralwedge-shaped spaces in the circumferential direction with the innerperipheral surface of the outer ring. The roller is disposed in each ofthe plural wedge-shaped spaces, connects the input rotor with the outputrotor so as to be capable of rotating together by engaging with theouter peripheral surface of the inner ring and the inner peripheralsurface of the outer ring, and releases the connection by disengagingthe engagement. The torque limiter includes the accommodating recesswhich is formed in the outer peripheral surface of the inner ring, andwhich accommodates the roller separated from a wedge-shaped space whenthe transmission torque from the input rotor to the output rotor exceedsthe upper limit, and thereby disengages the engagement of the rollerwith the outer peripheral surface of the inner ring and the innerperipheral surface of the outer ring. The torque limiter is providedwith the separation prevention means that prevents the roller in theaccommodating recess from being separated from the accommodating recessby centrifugal force in association with the rotation of the inputrotor.

The one-way clutch includes the torque limiter, and therefore when thetransmission torque from the input rotor to the output rotor exceeds theupper limit (the input rotor is connected to the output rotor to be putinto a locked state), the torque limiter releases the connection betweenthe input rotor and the output rotor. When the input rotor rotates in astate where the roller is accommodated in the accommodating recess, andthe roller moves out of the accommodating recess by the centrifugalforce, there is a possibility of the engagement of the roller with theinner ring outer peripheral surface (i.e., the outer peripheral surfaceof the inner ring) and the outer ring inner peripheral surface (i.e.,inner peripheral surface of the outer ring) again. However, the torquelimiter that is one example of the present invention includes theseparation prevention means that prevents the roller from beingseparated from the accommodating recess, and therefore such the problemscan be solved.

The separation prevention means may be constructed such that the controlsection that controls the movement of the roller which is accommodatedin the accommodating recess to the radial outside is protruded in theedge of the accommodating recess in the circumferential direction.According to such the structure, if the roller is separated from theaccommodating recess by centrifugal force due to the rotation of theinput rotor, the control section becomes an obstacle to prevent theseparation. Therefore, the engagement of the roller with the inner ringouter peripheral surface and the outer ring inner peripheral surfaceagain can be prevented suitably.

The cage that has a pocket which can accommodate the roller andmaintains circumferential spacing of plural rollers and the elasticmember that has a compression spring which biases the roller in thepocket toward the narrowing direction of the wedge-shaped space areprovided between the inner ring outer peripheral surface and the outerring inner peripheral surface. The separation prevention means may beconstructed by forming the accommodating recess in a depth in which theroller can be positioned in the radial inside with respect to theelastic member. According to the above structure, when the rollerseparates from the pocket of the cage to enter into the accommodatingrecess, the elastic member extends to be positioned in the radialoutside of the roller. Therefore, if the roller is separated from theaccommodating recess to the radial outside by centrifugal force inassociation with the rotation of the input rotor, the elastic memberbecomes an obstacle, and the separation can be prevented.

The elastic member may be provided with a block member that blocks atleast a part of the accommodating recess which accommodates the roller.According to the above structure, when the elastic member is disposed inthe radial outside of the roller that enters into the accommodatingrecess as described above, the block member that is attached to theelastic member can block at least a part of the accommodating recess andsecurely prevent the separation of the roller.

Hereinafter, a third embodiment through a fifth embodiment of thepresent invention will be described in detail with reference to attacheddrawings. FIG. 9 is a schematic side view that shows a wind powergenerating device according to the third embodiment of the presentinvention.

In FIG. 9, the wind power generating device 1 further includes an inputrotor 5 that is provided so as to be capable of rotating together withthe output shaft 35 of the speed up gears 3, an output rotor 6 that isprovided so as to be capable of rotating together with the drive shaft41 of the generator 4, a one-way clutch 7 that is disposed between theinput rotor 5 and the output rotor 6, a pair of rolling bearings 8 thatare disposed on axial sides of the one-way clutch 7, and an inertia mass9 that is provided so as to be capable of rotating together with theoutput rotor 6. The one-way clutch 7 and the rolling bearings 8 areconstructed to transmit the rotation of the output shaft 35 to the driveshaft 41 through the input rotor 5 and the output rotor 6. Here, thewind power generating device 1 of the present embodiment is constructedsuch that the rolling bearings 8 are disposed in the axial sides of theone-way clutch 7; however, a rolling bearing 8 may be disposed in onlyone axial side of the one-way clutch 7.

FIG. 10 is the same as FIG. 3, except for the inertia mass 9. FIG. 4also shows the one-way clutch 7 according to the third embodiment.

In FIG. 9 and FIG. 10, the inertia mass 9 is formed in a cylindricalshape and fitted and secured onto the cylindrical section 61 of theoutput rotor 6. The inertia mass 9 is designed so that an angularacceleration ω dot a by the deceleration of the output rotor 6 which iscalculated by the following equation (1) becomes smaller than an angularacceleration ω dot b by the deceleration of the output rotor 6 under anactual usage environment.ωdot a=T/I  (1)where T is a torque for electric power generation, and I is inertiamoment of the rotor of the generator and the inertia mass. In otherwords, the inertia mass 9 is designed so that the inertia moment I ofthe output rotor 6 and the rotor 42 of the generator 4 becomes large inorder to reduce the angular acceleration ω dot a in the above equation(1) to be smaller than the angular acceleration ω dot b under the actualusage environment. When actual measured values of the rotation speed cobof the output rotor 6 are plotted on a graph, the values show a waveformthat varies up and down with small amplitude as shown in FIG. 11.Therefore, when the slope of the line D that is drawn so as to passslightly above peaks of the amplitude is set as the angular accelerationω dot b under the actual usage environment the inertia mass 9 canpreferably be designed.

FIG. 12 is a graph that shows rotational fluctuations of the outputshaft of the speed up gears 3 and the rotor 42 of the generator 4. Asshown in FIG. 12, if the wind force decreases and the rotation speed ofthe output shaft 35 rapidly decreases, the rotor 42 does not rapidlydecreases the rotation speed in association with the output rotor 6through the drive shaft 41 but continues to rotate with gradualdeceleration due to the inertia. Accordingly, in a case where the windforce rapidly fluctuates, the rotational fluctuations of the rotor 42can be reduced.

The wind power generating device 1 that is constructed as describedabove produces a similar effect to the wind power generating device 1 ofthe first and the second embodiments.

In addition, the output rotor 6 is provided with the inertia mass 9 soas to be capable of rotating together, and therefore the inertia momentI of the output rotor 6 can be increased. Accordingly, the one-wayclutch 7 releases the connection between the input rotor 5 and theoutput rotor 6, and when the output rotor 6 rotates with decreased speeddue to the inertia of the rotor 42, the angular acceleration ω dot a bythe deceleration becomes small. Therefore, the rotation speed of theoutput rotor 6 can be prevented from rapidly decreasing. That is, evenif the wind force decreases and the rotation speed of the main shaft 2rapidly decreases, the rotor 42 of the generator 4 continues to rotatetogether with the output rotor 6 by inertia, and therefore averagerotation speed of the rotor 42 can be improved effectively. Accordingly,power generation efficiency of the generator 4 can be improved more.

FIG. 13 is a cross-sectional view that shows a connection part betweenan output shaft of speed up gears and a drive shaft of a generator in awind power generating device according to a fourth embodiment of thepresent invention. In FIG. 13, the wind power generating device 1 of thepresent embodiment includes an electromagnetic clutch 11 that connectsthe output rotor 6 with the inertia mass 9 so as to be capable ofrotating together during energization and releases the connection innon-energization, detection means (detection device) 12 that detects therotation speed of the output rotor 6, and control means (control device)13 that controls the energization of the electromagnetic clutch 11.

The electromagnetic clutch 11 includes a clutch housing 14 that isdisposed between the cylindrical section 61 of the output rotor 6 andthe inertia mass 9, a multiple-disc clutch 15 that is disposed betweenthe clutch housing 14 and the cylindrical section 61, an electromagnet16 that is disposed on one axial side of the multiple-disc clutch 15,and a biasing member 17 that is disposed on another axial side of themultiple-disc clutch 15. The clutch housing 14 has a cylindrical housingbody 14 a that is fitted and secured in the cylindrical section 61 andan annular section 14 b that extends from one axial end of the housingbody 14 a to a radial inside.

The multiple-disc clutch 15 is constructed such that plural outer clutchdiscs 15 a and plural inner clutch discs 15 b are alternatively arrangedin the axial direction. The outer clutch discs 15 a are mounted in theinner periphery of the housing body 14 a through spline fitting to, bemovable in the axial direction. In addition, the inner clutch discs 15 bare mounted in the outer periphery of the cylindrical section 61 of theoutput rotor 6 through spline fitting to be movable in the axialdirection.

The electromagnet 16 is constructed with a yoke 16 a that is formed in aU-shape in cross section and a coil 16 b that is held in the yoke 16 a.The yoke 16 a is fixed to the outer periphery of a cylindricalsupporting member 19 that is fixed to the housing of the speed up gears3. The supporting member 19 is provided with a rolling bearing 20 thatsupports the inertia mass 9 for rotation. The rolling bearing 20 isformed to be a ball bearing that includes an inner ring 20 a which isfitted and secured onto the supporting member 19, an outer ring 20 bwhich is fitted and secured into the inertia mass 9, and plural balls(rolling elements) 20 c that are placed between the inner ring 20 a andthe outer ring 20 b so as to be capable of rolling. The rolling bearing20 is formed to be a ball bearing that uses a ball as a rolling element;however, the rolling bearing 20 may be formed to be a roller bearingthat uses a roller as the rolling element.

The biasing member 17 is formed with a magnetic substance and mounted toa right end side of FIG. 13 in the inner periphery of the housing body14 a through spline fitting to be movable in the axial direction. Inaddition, the biasing member 17 is biased to the side of the flangesection 62 of the output rotor 6 by the biasing force of an elasticmember (not shown) and held in a non-biasing position shown in FIG. 13by abutting against a stopper ring 18 that is fixed in the innerperiphery of the housing body 14 a.

According to the above structure, when the coil 16 b of theelectromagnet 16 is not energized, the biasing member 17 is held in thenon-biasing position by the biasing force of the elastic member.Therefore, the outer clutch discs 15 a and the inner clutch discs 15 bare not in close contact with each other, or the multiple-disc clutch 15is in an OFF state, and therefore the connection between the outputrotor 6 and the inertia mass 9 is released. When the coil 16 b of theelectromagnet 16 is energized, the biasing member 17 is attracted to theelectromagnet 16 against the biasing force of the elastic member, andtherefore the biasing member 17 pushes the outer clutch discs 15 a andthe inner clutch discs 15 b to the side of the annular section 14 b ofthe clutch housing 14. Accordingly, the outer clutch discs 15 a and theinner clutch discs 15 b come into close contact with each other, or themultiple-disc clutch 15 is in an ON state, and therefore the outputrotor 6 and the inertia mass 9 are connected so as to be capable ofrotating together.

The detection means 12 detects the rotation speed of the drive shaft 41of the generator 4 which rotates together with the output rotor 6 inthis embodiment in order to detect the rotation speed of the outputrotor 6. Specifically, the detection means 12 is constructed with asensor that is disposed in the vicinity of the drive shaft 41 whichprotrudes to the right side in the drawing of the rotor 42 of thegenerator 4 shown in FIG. 9 and detects the rotation speed of the driveshaft 41. The detection means 12 may detect the rotation speed of therotor 42, the output shaft 35 of the speed up gears 3, or the outputrotor 6 itself, other than the drive shaft 41. In addition, thedetection means 12 may use a sensor that detects the rotation speed ofthe drive shaft 41 or the rotor 42 that is incorporated into thegenerator 4 in order to control the drive of the generator 4.

The control means 13 controls the energization of the coil 16 b of theelectromagnet 16 when the output rotor 6 starts to rotate. Specifically,the control means 13 controls not to energize the coil 16 b in order torelease the connection between the output rotor 6 and the inertia mass 9at startup of the rotation of the output rotor 6. When the detectionmeans 12 detects that the output rotor 6 reaches a specified rotationspeed (for example, 300 through 500 rpm) after the startup of therotation of the output rotor 6, the control means 13 controls toenergize the coil 16 b in order to connect the output rotor 6 with theinertia mass 9 so as to be capable of rotating together. Otherstructures of the present embodiment are the same as that of the thirdembodiment, and therefore the description is not repeated.

According to the wind power generating device 1 that is constructed asdescribed above, the electromagnetic clutch 11 is not energized and theconnection between the output rotor 6 and the inertia mass 9 is releaseduntil the output rotor 6 reaches the specified rotation speed at thestartup of the rotation, and therefore the running torque that isrequired to rotate the output rotor 6 up to the specified rotation speedcan be reduced. Accordingly, time that is required to rotate the rotor42 up to the specified rotation speed through the output rotor 6 and thedrive shaft 41 can be reduced, and therefore the power generationefficiency of the generator 4 can be improved more. When the detectionmeans 12 detects that the output rotor 6 reaches the specified rotationspeed after the startup of the rotation of the output rotor 6, theelectromagnetic clutch 11 is energized, and the output rotor 6 and theinertia mass 9 are connected so as to be capable of rotating together,and therefore the inertia moment of the output rotor 6 can be increased.Accordingly, when the one-way clutch 7 releases the connection betweenthe input rotor 5 and the output rotor 6, the rotor 42 of the generator4 does not rapidly decreases the rotation speed in association with theoutput rotor 6 but continues to rotate by the inertia, and therefore theaverage rotation speed of the rotor 42 can be increased. Accordingly,power generation efficiency of the generator 4 can be improved more.

FIG. 14 is a cross-sectional view that shows a connection part betweenan output shaft of speed up gears and a drive shaft of a generator in awind power generating device according to a fifth embodiment of thepresent invention. In FIG. 14 the wind power generating device 1 of thepresent embodiment includes a viscous fluid coupling 22 as analternative to the electromagnetic clutch 11 of the fourth embodiment.The viscous fluid coupling 22 is disposed between the cylindricalsection 61 of the output rotor 6 and the inertia mass 9 and includes aclutch housing 23, plural outer clutch discs 24 a, plural inner clutchdiscs 24 b, a biasing member 25, and a ball 26.

The clutch housing 23 has a cylindrical housing body 23 a that is fittedand secured in the cylindrical section 61 and an annular section 23 bthat extends from one axial end of the housing body. 23 a to a radialinside. Another axial side of the housing body 23 a is covered with acover member 27 that is formed from an annular plate. Annular sealmembers 28 a and 28 b are respectively provided in spacing between theannular section 23 b of the clutch housing 23 and the cylindricalsection 61 and spacing between the housing body 23 a and the covermember 27. An annular sealed space is formed between the housing body 23a and the cylindrical section 61.

A viscous fluid such as silicone oil is filled in the sealed space, andthe outer clutch discs 24 a and the inner clutch discs 24 b arealternatively arranged in the axial direction. The outer clutch discs 24a are mounted in the inner periphery of the housing body 23 a throughspline fitting to be movable in the axial direction. In addition, theinner clutch discs 24 b are mounted in the outer periphery of thecylindrical section 61 of the output rotor 6 through spline fitting tobe movable in the axial direction.

The biasing member 25 is mounted to a right end side of FIG. 14 in theinner periphery of the housing body 23 a through spline fitting to bemovable in the axial direction. One side surface of the biasing member25 is formed with an inclined surface 25 a that is inclined so thatthickness of the biasing member 25 in the axial direction graduallyincreases toward the radial outside. Accordingly, a wedge-shaped space Kis formed between the inclined surface 25 a of the biasing member 25 andthe cover member 27 so as to become narrower toward the radial outside.Plural balls 26 are accommodated in the wedge-shaped space K in thecircumferential direction. The biasing member 25 is always biased to theside of the flange section 62 of the output rotor 6 by the biasing forceof the elastic member (not shown) and held in a non-biasing positionshown in FIG. 14 by abutting against the ball 26. In the presentembodiment, a centrifugal clutch mechanism 29 is constructed with theouter clutch discs 24 a, the inner clutch discs 24 b, the biasing member25, and the ball 26.

According to the above structure, when the output rotor 6 rotates at lowspeed during the startup of the rotation, centrifugal force that isapplied to the ball 26 of the viscous fluid coupling 22 is small.Therefore, as shown in FIG. 14, the ball 26 is positioned in the radialinside of the wedge-shaped space K, and the biasing member 25 is held inthe non-biasing position by the biasing force of the elastic member.Therefore, the outer clutch discs 24 a and the inner clutch discs 24 bare not in close contact with each other, or the centrifugal clutchmechanism 29 is in an OFF state, and therefore the running torque of theoutput rotor 6 is transmitted to the inertia mass 9 by viscous drag ofthe viscous fluid.

In FIG. 14, when the output rotor 6 reaches a specified rotation speedto rotate at high speed, the centrifugal force that is applied to theball 26 of the viscous fluid coupling 22 becomes large. Therefore, theball 26 moves to the radial outside of the wedge-shaped space K alongthe inclined surface 25 a of the biasing member 25 by the centrifugalforce. In this case, the biasing member 25 is pushed to the side of theannular section 23 b of the clutch housing 23 by the ball 26, andtherefore the biasing member 25 pushes the outer clutch discs 24 a andthe inner clutch discs 24 b to the side of the annular section 23 bagainst the biasing force of the elastic member. Accordingly, the outerclutch discs 24 a and the inner clutch discs 24 b come into intimatecontact with each other, or the centrifugal clutch mechanism 29 is in anON state, and therefore the running torque of the output rotor 6 istransmitted to the inertia mass 9 through the centrifugal clutchmechanism 29.

FIG. 15 is a graph that shows rotational fluctuations of the outputrotor 6 and the inertia mass 9 of the present embodiment. As shown inFIG. 15, when the output rotor 6 rotates at low speed during the startupof the rotation, or when the running torque of the output rotor 6 istransmitted to the inertia mass 9 by viscous drag of the viscous fluid,the inertia mass 9 increases the speed with lower angular acceleration(slope of a broken line shown in FIG. 15) than the angular accelerationof the output rotor 6 (slope of a continuous line shown in FIG. 15). Inaddition, when the output rotor 6 reaches the specified rotation speedwe to rotate at high speed, or when the running torque of the outputrotor 6 is transmitted to the inertia mass 9 through the centrifugalclutch mechanism 29, the inertia mass 9 rotates together with the outputrotor 6 with the same rotation speed ωc. Other structures of the presentembodiment are the same as that of the third and the fourth embodiments,and therefore the description is not repeated.

According to the wind power generating device 1 that is constructed asdescribed above, when the output rotor 6 rotates at low speed during thestartup of the rotation, the running torque of the output rotor 6 istransmitted to the inertia mass 9 by viscous drag of the viscous fluid,and therefore the inertia mass 9 increases the speed with lower angularacceleration than the angular acceleration of the output rotor 6. Inother words, inertia torque by the inertia mass 9 which is applied tothe output rotor 6 at the startup of the rotation of the output rotor 6can be reduced, and therefore the running torque that is required toincrease the rotation speed of the output rotor 6 up to the specifiedrotation speed can be reduced. Accordingly, time that is required toincrease the rotation speed of the rotor 42 up to the specified rotationspeed through the output rotor 6 and the drive shaft 41 can be reduced,and therefore the power generation efficiency of the generator 4 can beimproved. In addition, when the output rotor 6 reaches the specifiedrotation speed to rotate at high speed, the running torque of the outputrotor 6 is transmitted to the inertia mass 9 through the centrifugalclutch mechanism 29. Accordingly, the output rotor 6 and the inertiamass 9 are connected so as to be capable of rotating together, andtherefore the inertia moment of the output rotor 6 can be increased.Therefore, when the one-way clutch 7 releases the connection between theinput rotor 5 and the output rotor 6, the rotor 42 of the generator 4does not rapidly decreases the rotation speed in association with theoutput rotor 6 but continues to rotate by the inertia, and therefore theaverage rotation speed of the rotor 42 can be increased, and the powergeneration efficiency of the generator 4 can be improved more.

The present invention is not limited to the above embodiments describedabove and can be changed appropriately to be practiced. For example, inthe present embodiment, the input rotor and the output rotor arerespectively provided to the output shaft and the drive shaft asseparate members; however, the input rotor and the output rotor mayintegrally be formed with the output shaft and the drive shaft,respectively. The output rotor is arranged on the radial outside of theinput rotor; however, the output rotor may be arranged on the radialinside of the input rotor. In this case, the one-way clutch may beformed with the outer ring inner peripheral surface as the cam surface,and the inner ring outer peripheral surface may be formed as thecylindrical surface. Furthermore, in this case, the inner ring outerperipheral surface may be formed in the outer peripheral surface of theoutput rotor, and the output rotor may be used as the inner ring.

In addition, the output rotor is formed as the outer ring of the one-wayclutch and the outer ring of the rolling bearing; however, these outerrings may be provided to the output rotor as separate members. Therolling bearing that is disposed between the input rotor and the outputrotor is constructed as the cylindrical roller bearing in order to movethe output rotor in the axial direction; however, the roiling bearingmay be constructed as a ball bearing in a case where the output rotor isnot moved in the axial direction.

The cage of the one-way clutch comes into contact with the inner ring ofthe rolling bearing; however, the outer ring of the rolling bearing maybe provided to the output rotor as a separate member, and the outer ringmay come into contact with the cage of the one-way clutch. The powergenerating device of the present embodiment is exemplified in a case ofusing wind force as external force; the power generating device of thepresent embodiment may be applicable to the power generating device thatgenerates electricity by using other external force such as waterpoweror thermal power.

In the third embodiment, the inertia mass is provided to the outputrotor as a separate member; however, the inertia mass may be integrallyframed with the output rotor. In addition, when the output rotor isarranged in the radial inside of the input rotor, the inertia mass maybe provided in the axial end of the output rotor so as not to interferewith the one-way clutch or the rolling bearing.

What is claimed is:
 1. A power generating device comprising: speed upgears including a main shaft that rotates by external force, a rotationtransmission mechanism that receives rotation of the main shaft toincrease speed of the rotation of the main shaft, and a roller bearingthat rotatably supports an output shaft that outputs running torque ofthe rotation transmission mechanism; a generator including a drive shaftwhich is rotated by receiving rotation of the output shaft andconfigured to generate electricity in connection with rotation of arotor which rotates together with the drive shaft; an input rotorprovided to the output shaft to be capable of rotating together with theoutput shaft; an output rotor provided to the drive shaft to be capableof rotating together with the drive shaft and concentrically arranged ona radial inside or a radial outside of the input rotor; a one-way clutchdisposed between the input rotor and the output rotor, the one-wayclutch being configured to connect the input rotor with the output rotorto rotate together with the input rotor and the output rotor when arotation speed of the input rotor exceeds a rotation speed of the outputrotor, and the one-way clutch being configured to release a connectionbetween the input rotor and the output rotor when the rotation speed ofthe input rotor falls below the rotation speed of the output rotor; anda rolling bearing disposed between the input rotor and the output rotorand configured to support the input rotor and the output rotor so thatthe input rotor and the output rotor relatively rotate with each other,wherein: the one-way clutch includes an outer peripheral surface of aninner ring, an inner peripheral surface of an outer ring, and a rollerarranged in each of plural wedge-shaped spaces formed between the outerperipheral surface of the inner ring and the inner peripheral surface ofthe outer ring, the one-way clutch is configured to connect the inputrotor with the output rotor to rotate together with the input rotor andthe output rotor by engaging the roller with the outer peripheralsurface of the inner ring and the inner peripheral surface of the outerring, the one-way clutch is configured to release the connection betweenthe input rotor and the output rotor by disengaging engagement of theroller with the outer peripheral surface of the inner ring and the innerperipheral surface of the outer ring, the one-way clutch includes anannular cage configured to hold the plural rollers at specified spacingalong a circumferential direction, a pair of the rolling bearings isdisposed between the input rotor and the output rotor, the pairedrolling bearings are arranged on respective axial sides of the one-wayclutch so that each of the paired rolling bearings is adjacent to theone-way clutch and an axial end of each of the paired rolling bearingsis capable of coming into contact with a corresponding one of axial endfaces of the annular cage of the one-way clutch, the paired rollingbearings are a pair of cylindrical roller bearings that include pluralcylindrical rollers and a portion with which end faces of the pluralcylindrical rollers in an axial direction come into sliding contact, theaxial end faces of the annular cage come into contact with the portionin the pair of the cylindrical roller bearings, the one-way clutch isprovided with a torque limiter configured to release the connectionbetween the input rotor and the output rotor when transmission torquefrom the input rotor to the output rotor exceeds an upper limit, thetorque limiter is provided with an accommodating recess that is formedin the outer peripheral surface of the inner ring, and that accommodatesthe roller separated from the wedge-shaped space, when the transmissiontorque exceeds the upper limit, to disengage the engagement of theroller with the outer peripheral surface of the inner ring and the innerperipheral surface of the outer ring, a plurality of cam surfaces areformed in the outer peripheral surface of the inner ring, and theaccommodating recess is formed in a position between two of theplurality of cam surfaces that are closest to each other in thecircumferential direction.
 2. The power generating device according toclaim 1, wherein the inner peripheral surface of the outer ring of theone-way clutch is a cylindrical surface, the cylindrical roller bearingincludes a raceway surface of an outer ring of the cylindrical rollerbearing where the cylindrical roller bearing rolls, the output rotor isarranged on a radial outside of the input rotor, and the innerperipheral surface of the outer ring of the one-way clutch and theraceway surface are formed in an inner peripheral surface of the outputrotor.
 3. The power generating device according to claim 2, wherein theoutput rotor is removably secured to the drive shaft and arranged to bemovable in the axial direction with respect to the input rotor.
 4. Thepower generating device according to claim 1, wherein the outerperipheral surface of the inner ring is provided in the input rotor, andthe torque limiter is provided with a separation prevention device thatprevents the roller in the accommodating recess from being separatedfrom the accommodating recess by centrifugal force due to rotation ofthe input rotor.
 5. The power generating device according to claim 4,wherein a pocket configured to be capable of accommodating the roller isprovided between the outer peripheral surface of the inner ring and theinner peripheral surface of the outer ring, a cage configured to holdthe rollers at specified spacing along the circumferential direction andan elastic member configured to bias the roller in the pocket toward anarrowing direction of the wedge-shaped space are provided between theouter peripheral surface of the inner ring and the inner peripheralsurface of the outer ring, and the accommodating recess is formed tohave a depth in which the roller is positioned in a radial inside withrespect to the elastic member.
 6. The power generating device accordingto claim 5, wherein the elastic member is provided with a block memberthat blocks at least a part of the accommodating recess thataccommodates the roller.
 7. The power generating device according toclaim 4, wherein the separation prevention device is constructed suchthat a restricting section that restricts the movement of the rolleraccommodated in the accommodating recess to the radial outside isprotruded in an edge of the accommodating recess in the circumferentialdirection.
 8. The power generating device according to claim 7, whereina pocket configured to be capable of accommodating the roller isprovided between the outer peripheral surface of the inner ring and theinner peripheral surface of the outer ring, a cage configured to holdthe rollers at specified spacing along the circumferential direction andan elastic member configured to bias the roller in the pocket toward anarrowing direction of the wedge-shaped space are provided between theouter peripheral surface of the inner ring and the inner peripheralsurface of the outer ring, and the accommodating recess is formed tohave a depth in which the roller is positioned in a radial inside withrespect to the elastic member.
 9. The power generating device accordingto claim 8, wherein the elastic member is provided with a block memberthat blocks at least a part of the accommodating recess thataccommodates the roller.
 10. The power generating device according toclaim 1, further comprising: an inertia mass provided to be capable ofrotating together with the output rotor.
 11. The power generating deviceaccording to claim 10, wherein the inner peripheral surface of the outerring of the one-way clutch is a cylindrical surface, the cylindricalroller bearing includes a raceway surface of an outer ring of thecylindrical roller bearing where the cylindrical roller bearing rolls,the output rotor is arranged on a radial outside of the input rotor, andthe inner peripheral surface of the outer ring of the one-way clutch andthe raceway surface are formed in an inner peripheral surface of theoutput rotor.
 12. The power generating device according to claim 11,wherein the output rotor is removably secured to the drive shaft andarranged to be movable in the axial direction with respect to the inputrotor.
 13. The power generating device according to claim 10, furthercomprising: an electromagnetic clutch configured to connect the outputrotor with the inertia mass so that the output rotor and the inertiamass rotate together during energization and to release the connectionbetween the output rotor and the inertia mass in non-energization; adetection device configured to detect the rotation speed of the outputrotor; and a control device configured to control to put theelectromagnetic clutch into non-energization state at startup ofrotation of the output rotor and to control to energize theelectromagnetic clutch when the detection device detects that the outputrotor reaches a specified rotation speed after the startup of therotation of the output rotor.
 14. The power generating device accordingto claim 10, further comprising: a viscous fluid coupling disposedbetween the output rotor and the inertia mass, wherein the viscous fluidcoupling includes; i) viscous fluid that transmits a running torque ofthe output rotor to the inertia mass by viscous drag during low-speedrotation of the output rotor, and ii) a centrifugal clutch mechanismthat transmits the running torque of the output rotor to the inertiamass by using centrifugal force in association with high-speed rotationof the output rotor during the high-speed rotation of the output rotor.